Scrubber box and methods for using the same

ABSTRACT

A scrubber box is provided that includes a tank adapted to receive a substrate for cleaning, supports outside of the tank and adapted to couple to ends of scrubber brushes disposed within the tank, a motor mounted to each of the supports and adapted to rotate the scrubber brushes, a base to which the supports are pivotally mounted via spherical bearings adapted to permit toe-in of the scrubber brushes, a brush gap actuator adapted, via a crank and rocker mechanism, to substantially simultaneously pivot the supports toward or away from each other so as to permit the scrubber brushes to substantially simultaneously achieve or break contact with the substrate, and a toe-in actuator adapted to move two of the spherical bearings toward or away from each other so as to adjust a toe-in angle between the scrubber brushes.

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/976,012, filed Oct. 28, 2004, which claimspriority to U.S. Provisional Application Ser. No. 60/514,937, filed Oct.28, 2003 and entitled “Scrubber Box And Methods For Using The Same”.Each of these applications is hereby incorporated by reference herein inits entirety for all purposes.

RELATED APPLICATIONS

The present application is related to the following commonly-assigned,co-pending U.S. patent applications, both of which are herebyincorporated herein by reference in their entirety for all purposes:

U.S. patent application Ser. No. 10/283,030, filed Oct. 29, 2002(Attorney Docket No. 5408) and entitled “Methods And Apparatus ForDetermining Scrubber Brush Pressure.”

U.S. patent application Ser. No. 09/580,880, filed May 30, 2000(Attorney Docket No. 3874) and entitled “Roller That Avoids SubstrateSlippage.”

FIELD OF THE INVENTION

The present invention relates generally to electronic devicemanufacturing, and more particularly to a scrubber box for cleaning thindiscs such as semiconductor substrates or wafers, compact discs, glasssubstrates and the like.

BACKGROUND OF THE INVENTION

Known devices, sometimes referred to as scrubbers, are often employed toclean semiconductor substrates at one or more stages of an electronicdevice manufacturing process. For example, a scrubber may be employed toclean a substrate after chemical mechanical polishing (CMP) of thesubstrate. Known scrubbers employ one or more scrubber brushes that arerotated while in contact with the substrate to thereby clean thesubstrate.

While a number of scrubber systems exist in the art, a need remains forimproved scrubber designs.

SUMMARY OF THE INVENTION

In a first aspect of the invention, an apparatus is provided thatincludes a linkage adapted to support scrubber brushes. The linkageincludes a base and brush supports pivotally coupled to the base. Theapparatus also includes an actuator adapted to pivot the brush supportsin concert such that scrubber brushes supported by the brush supportssubstantially simultaneously achieve contact with, or break contactwith, respective major surfaces of a substrate.

In a second aspect of the invention, a method is provided that includesinserting a substrate into a scrubber box, concurrently pivotingopposing brush supports together through a single arc to engage asubstrate with brushes supported by the brush supports, and rotating thebrushes to clean the substrate.

In a third aspect of the invention, an apparatus is provided thatincludes a brush support adapted to rotatably hold a scrubber brush, amotor adapted to rotate the scrubber brush held in the brush support, anactuator coupled to the brush support and adapted to move the brushsupport to allow the scrubber brush to engage a substrate, and acontroller coupled to the motor and actuator. The controller is adaptedto locate a zero point position of the scrubber brush based upon achange in torque exerted by the motor to rotate the scrubber brush asthe actuator moves the brush support.

In a fourth aspect of the invention, an apparatus is provided thatincludes a base, brush supports adapted to rotatably support scrubberbrushes, spherical bearings slideably mounted to the base and coupled tothe brush supports, and an actuator disposed between the sphericalbearings. The actuator is adapted to adjust a toe-in position of thescrubber brushes by moving the brush supports.

In a fifth aspect of the invention, an apparatus is provided thatincludes a rotary shaft adapted to receive a scrubber brush, a rotarysupport, and a fluid lubricated bearing mounted on the rotary supportand coupled to the rotary shaft. The rotary shaft includes anaxially-disposed process fluid channel and the fluid lubricated bearingincludes a fluid lubrication entry point coupled to the process fluidchannel of the rotary shaft.

In a sixth aspect of the invention, an apparatus is provided thatincludes a roller adapted to rotate a substrate in a scrubber box, asensor adapted to indicate an occurrence of a defined amount of rotationof the substrate, and a controller coupled to the sensor and adapted todetermine a rate of rotation of the substrate.

In a seventh aspect of the invention, an apparatus is provided thatincludes a roller adapted to rotate a substrate in a scrubber box tank,a roller support, and a fluid lubricated bearing mounted on the rollersupport and coupled to the roller. The roller includes anaxially-disposed process fluid channel and the fluid lubricated bearingincludes a fluid lubrication entry point coupled to the process fluidchannel of the roller.

In an eighth aspect of the invention, a scrubber box is provided thatincludes a tank adapted to receive a substrate for cleaning, supportsoutside of the tank and adapted to couple to ends of scrubber brushesdisposed within the tank, a motor mounted to each of the supports andadapted to rotate the scrubber brushes, a base to which the supports arepivotally mounted via spherical bearings adapted to permit toe-in of thescrubber brushes, a brush gap actuator adapted, via a crank and rockermechanism, to substantially simultaneously pivot the supports toward oraway from each other so as to permit the scrubber brushes tosubstantially simultaneously achieve or break contact with thesubstrate, and a toe-in actuator adapted to move two of the sphericalbearings toward or away from each other so as to adjust a toe-in anglebetween the scrubber brushes.

Numerous other aspects are provided, as are apparatus, systems andcomputer program products in accordance with these and other aspects ofthe invention. Each computer program product described herein may becarried by a medium readable by a computer (e.g., a carrier wave signal,a floppy disc, a compact disc, a DVD, a hard drive, a random accessmemory, etc.).

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are a side perspective view and simplified top view,respectively, of an inventive scrubber box provided in accordance withthe present invention.

FIG. 2 is a partial perspective view, rotated by 180° relative to FIG.1A, showing internal components of the inventive scrubber box.

FIG. 3 is a partial, perspective view of an exemplary crank and rockermechanism for placing scrubber brushes in or out of contact with asubstrate in accordance with the invention.

FIG. 4 is a perspective view of an inventive bearing arrangement thatmay be employed to adjust brush toe-in-angle in accordance with thepresent invention.

FIG. 5 is a partial, cross-sectional view of an exemplary sphericalbearing that may be employed within the inventive scrubber box.

FIG. 6 is a cross-sectional view of a portion of an inventive rotaryshaft that may be employed at an end of a scrubber brush in accordancewith the present invention.

FIG. 7 is a side, schematic view of an inventive roller arrangement thatmay be employed within the scrubber box of FIGS. 1A-2 to support and/orrotate a substrate.

FIG. 8 is a side, cross-sectional view of an exemplary inventive idlerroller.

FIG. 9 is a side perspective view of an exemplary drive roller providedin accordance with another embodiment of the invention.

FIG. 10A is a partial cross-sectional view of a first exemplaryembodiment of a polymer capped motor shaft provided in accordance withthe invention.

FIG. 10B illustrates an alternative polymer cap arrangement for themotor of FIG. 10A.

FIG. 11 is a flowchart illustrating an example embodiment of a brush gapconfiguration method according to the present invention.

DETAILED DESCRIPTION Inventive Scrubber Box Linkage

FIGS. 1A and 1B are a side perspective view and simplified top view,respectively, of an inventive scrubber box 101 provided in accordancewith the present invention. FIG. 2 is a partial perspective view,rotated by 180° relative to FIG. 1A, showing internal components of theinventive scrubber box 101.

Referring to FIGS. 1A-2, the scrubber box 101 includes a tank 103 and alinkage 105. The linkage 105 is external to (i.e., outside of) the tank103 of the scrubber box 101 and may be employed for convenient andaccurate actuation/movement of one or more scrubber brushes 106 a-b(FIG. 1B) located inside the tank 103 relative to the major surfaces ofa substrate W (FIGS. 1B and 2). The linkage 105 may comprise a firstsupport 107 for rotationally supporting the first scrubber brush 106 aat both ends of the first scrubber brush 106 a, and a second support 109for rotationally supporting the second scrubber brush 106 b at both endsof the second scrubber brush 106 b. Drive motors 111, such as directdrive servo motors, for rotating each scrubber brush 106 a-b may also bemounted, one on each support 107, 109 outside the tank 103. For example,each motor 111 may be oriented in line with an end of a scrubber brush106 a-b and mounted to the support 107, 109 where the support 107, 109rotationally supports the end of the scrubber brush 106 a-b. The linkage105 may further comprise a base 113, also disposed outside the tank 103,to which each of the first and second supports 107, 109 may be coupled(e.g., in common so as to facilitate precise and/or cooperativepositioning and/or orientation of the scrubber brushes 106 a-b relativeto an anticipated plane of rotation of the substrate W as describedbelow) and relative to which the first and second supports 107, 109 maybe adapted to pivot (e.g. upward and inward toward one another, and/ordownward and outward away from one another).

In operation, the first and second supports 107, 109 may be movedsimultaneously through respective arcs A₁, A₂ (FIG. 1A) relative to thebase 113 (e.g., via a plurality of spherical and/or gimbal-type bearingsas described further below). Such movement may cause the first andsecond scrubber brushes 106 a-b to close against the substrate W asshown in FIG. 1B, or to cause a gap (not shown) to be opened between thefirst and second scrubber brushes 106 a-b to allow insertion and/orremoval of the substrate W from the scrubber box 101. For example, afirst actuator 115 may be mounted to the base 113, and may be caused toprecisely move the first and second supports 107, 109 in concert suchthat the first and second scrubber brushes 106 a-b may (1)simultaneously achieve contact with, or break contact with, respectivemajor surfaces of the substrate W; and/or (2) achieve similar degrees ofcompression against respective major surfaces of the substrate W whenclosed against the substrate W.

In some embodiments, the path of the first and second scrubber brushes106 a-b follow arcs A₁, A₂ (FIG. 1A) which (in contrast to the arcs A₁,A₂ depicted in FIG. 1A) may be disposed so as to form a singlecontinuous arc. In other words, the path of the first and secondscrubber brushes 106 a-b may comprise an arc wherein the first scrubberbrush 106 a moves along one half of the single arc and the secondscrubber brush 106 b moves along the other half of the arc. This singlearc path of motion may help provide a symmetric and consistentinteraction between the scrubber brushes 106 a-b and the substrate W.

In some embodiments, the scrubber box 101 may include a controller 104(FIG. 1B) for directing operation of the motors 111, actuators 115, 129(FIG. 4), and/or other devices. The controller 104 may be operative toexecute program instructions provided to it in the form of softwarecode. In some embodiments, the controller 104 may include circuitry orotherwise be adapted to measure the torque exerted by the motors 111,actuators 115, 129, and/or other devices.

In one or more embodiments, the first actuator 115 comprises a harmonicdrive or other suitable motor or drive mechanism 116, and is coupled tothe first and second supports 107, 109 via a crank and rocker mechanism117 (FIG. 3) to provide equivalent motion of both supports. FIG. 3 is apartial, perspective view of an exemplary crank and rocker mechanism 117provided in accordance with the invention. The crank and rockermechanism 117 may include a crank shaft linkage mechanism 117 a with atwo-eccentric crank 118 (FIG. 2) driven by the first actuator 115 (FIG.1A). In one particular embodiment, a first crank arm 120 a is driven byone of the eccentrics of the crank 118 (e.g., eccentric 122 a in FIG. 2)so as to rotate and/or move the first support 107, and a second crankarm 120 b is driven by the other eccentric of the crank 118 (e.g.,eccentric 122 b in FIG. 2) so as to rotate and/or move the secondsupport 109. Different embodiments for moving the supports 107, 109 maybe provided, such as a cam with two cam followers, lead screws, etc.

Additionally, in one or more embodiments, clearance holes (not shown)may be formed in the tank 103 to achieve rotational coupling between thebrushes 106 a-b and the supports 107, 109. A geometrically compliantcoupling element 119 (FIGS. 1A and 2), such as a bellows, may bedisposed around each such hole and mounted between the tank 103 and thesupport 107, 109. Such an arrangement may (1) permit relative motion ofthe scrubber brushes 106 a-b relative to the walls of the tank 103; (2)protect the substrate W against particulate contamination that mightotherwise pass into the interior of the tank 103 through the holes inthe tank walls; and/or (3) permit a fluid level in the tank 103 to reachor exceed the level of the holes while preventing fluid from drainingtherethrough.

Maintaining Consistent Scrubbing Force Via Torque Monitoring AndZero-Point Calibration

In one or more embodiments of the invention, a scrubbing force imposedby the first and second scrubbing brushes 106 a-b (FIG. 1B) on the majorsurfaces of the substrate W (FIG. 2) may be kept consistent despiteprogressive wear of scrubbing surfaces of the brushes 106 a-b and/orvariation in locations or orientations of components of the scrubber box101 due to unavoidable manufacturing or assembly tolerances. Forexample, a desired amount of scrubbing force F_(s) to be imparted in anormal direction against a major surface of the substrate W by one ofthe first and second scrubbing brushes 106 a-b supported by the firstand second supports 107, 109 may be determined in advance, and may bedefined by the following equation:

$F_{s} = \frac{{{T_{s}({idle})} - {T_{s}({brushing})}}}{r_{b}({compressed})}$

where T_(s)(idle) represents an initial torque present in a shaft of amotor (e.g., motor 111) rotationally driving a scrubbing brush 106 a-bin an open (non-contact) position relative to the substrate W,r_(b)(compressed) represents a distance (smaller than an uncompressedradius of the brush) between the axis of rotation of the brush 106 a-band the major surface of the substrate W after the brush 106 a-b hasbeen compressed against a major surface of the substrate W, andT_(s)(brushing) represents the torque in the shaft of the motor as thebrush 106 a-b rotates and scrubs the substrate W while the axis of thebrush 106 a-b is located at r_(b)(compressed) from the substrate's majorsurface.

T_(s)(idle) may be measured initially, such as before the scrubber box101 is placed into service, and/or at a later time when recalibration ofthe scrubber box 101 is desired. Paired values for r_(b)(compressed) andT_(s)(brushing) may be obtained experimentally (e.g., based oncalibration tests performed on the particular model of scrubber brushused).

A zero point for a scrubbing brush 106 a-b relative to the major surfaceof the substrate W, which corresponds to the largest value of r_(b)consistent with the brush 106 a-b still contacting the major surface ofthe substrate W, may be found by monitoring and/or measuring the torqueT_(s) of the motor that drives the brush 106 a-b as the brush 106 a-b ismoved relative to the substrate W. For example, a rotating brush may beplaced in an initial position at which the rotating brush is compressedagainst the major surface of the substrate W, and the torque T_(s) maybe monitored as the rotating brush is backed away from the substrate Wto determine the position of the respective support 107, 109 relative tothe base 113 when the torque T_(s) reaches T_(s)(idle). This occurs atthe point when a gap between the brush 106 a-b and the major surface ofthe substrate W is beginning to be formed. Alternatively, a rotatingbrush may be placed in an initial position at which the rotating brushis spaced apart from the major surface of the substrate W, and thetorque T_(s) may be monitored as the rotating brush is moved toward thesubstrate W to determined the position of the respective support 107,109 relative to the base 113 when the torque T_(s) begins to rise from abaseline value of T_(s)(idle). This occurs at the point when a gapbetween the brush 106 a-b and the major surface of the substrate W hasjust been closed.

Once the zero point for a scrubbing brush 106 a-b is found, therespective support 107, 109 may be moved toward the substrate W alongthe base 113 by an increment corresponding to that degree of compressionin the brush 106 a-b which the prior testing indicated corresponds tothe desired amount of scrubbing force F_(s). For example, a scrubbingbrush 106 a-b may be moved toward the major surface of the substrate Wto the extent of a predetermined distance obtained by subtracting r_(b)(compressed) from the (known) radial outline dimension of the brush usedin the previous scrubbing force calibration testing described above.Additional torque monitoring techniques that may be employed aredescribed in previously incorporated U.S. patent application Ser. No.10/283,030, filed Oct. 29, 2002 (Attorney Docket No. 5408). As indicatedin U.S. patent application Ser. No. 10/283,030, the scrubber box 101 mayinclude a torque monitor to make the above described measurements.

Toe-in of Brush Rollers

The present invention also provides for convenient adjustment of atoe-in angle between the first and second brushes 106 a-b. For example,on a side 121 (FIG. 1A) of the tank 103 opposite to where the firstactuator 115 urges the first and second supports 107, 109 through theirrespective arcs A₁, A₂ relative to the base 113, the scrubber box 101may comprise a first bearing 123 (FIG. 2) slideably mounted on the base113 for pivotally supporting the first support 107 and a second bearing125 (FIG. 2), also slideably mounted on the base 113, for pivotallysupporting the second support 109.

As illustrated in FIG. 4, in one or more embodiments, a second actuator129 may be fixedly mounted to the base 113 between the first and secondslideably mounted bearings 123, 125. The second actuator 129 may beadapted to provide accurate adjustment of the distance between the firstand second bearings 123, 125 and thereby, provide precise adjustment ofthe toe-in angle. Thus, as shown in FIG. 4, the first and secondbearings 123, 125 may be adapted to slide or reciprocate relative to oneanother (e.g. such that a toe-in angle between the first and secondbrushes 106 a-b increases and/or decreases along with a distance betweenthe first and second bearings 123, 125).

In some embodiments, the second actuator 129 may comprise a lead screw401 (FIG. 4) adapted to symmetrically change the distance between thebearings 123, 125. For example, such a lead screw may comprise left andright threads (not shown) for cooperation with complementary collars403, 405 on the first and second bearings 123, 125.

Appropriate fasteners or other retaining mechanisms (e.g., screws 407a-d) may be used to slideably mount the first and second bearings 123,125 to the base 113. Such fasteners may be loosened to allow positionadjustment of the bearings 123, 125; and then tightened to retain theadjusted bearing position.

To flexibly accommodate both toe-in angle adjustment and smooth pivotingmotion of the supports 107, 109 relative to the base 113, some or all ofthe bearings between the supports 107, 109 and the base 113, includingthe first and second bearings 123, 125, may comprise spherical and/orgimbal-type support surfaces and/or low-friction plastic materials suchas polytetrafluoroethylene (PTFE). For example, FIG. 5 is a partial,cross-sectional view of an exemplary spherical bearing 127 that may beemployed for the first and/or second bearings 123, 125 (and/or for oneor both of the bearings 128 a, 128 b (FIG. 1A) that couple to thesupports 107, 109 on the first actuator 115 side of the scrubber box101).

Additional and/or alternative toe-in adjustment mechanisms also may beemployed, as described, for example, in previously incorporated U.S.patent application Ser. No. 10/283,030, filed Oct. 29, 2002 (AttorneyDocket No. 5408).

Water-Lubrication of Rotary Bearings

It is known to direct a flow of fluid to the major surfaces of asubstrate within a scrubber tank by directing a flow of fluid underpressure into a scrubber brush. For example, an axially-disposed fluidentry port at a motor end of a scrubber brush may be employed to causepressurized fluid to flow radially out of the brush via pores adjacentthe substrate-scrubbing surfaces of the brush. In one or moreembodiments of the present invention, such a pressurized flow of fluidinto a scrubber brush may additionally be employed to lubricate one ormore bearings of the inventive scrubber box 101. For example, a rotarysupport 130 (FIG. 1B) may be provided (e.g., at the non-motor end 121 ofthe scrubber brush box 101) and may include one or morewater-lubricatable bearings (described below with reference to FIG. 6)),and hydraulic communication may be provided between the water-lubricatedbearings and a fluid-containing internal portion of a scrubber brush.

FIG. 6 is a cross-sectional view of a portion of an inventive rotarysupport 130 that may be employed, for example, at the non-motor end 121(FIG. 1B) of a scrubber brush 106 a and/or 106 b. With reference to FIG.6, the rotary support 130 includes a rotary shaft 131 that protrudesinto an enclosure 133 formed within the rotary support 130. A fluid port137 may be axially disposed in the rotary shaft 131 so as to terminateat the enclosure 133 and permit a flow of fluid into the enclosure 133.For example, a fitting or other coupling (not shown) may be coupled tothe rotary support 130 and employed to supply fluid (e.g., water) to thefluid port 137. In one embodiment of the invention, 2-3% of the totalflow of fluid through the fluid port 137 may be directed into theenclosure 133 (e.g., by traveling left to right along the fluid port inFIG. 6 and as indicated by arrow 135). Other amounts of the total fluidflow also may be used. The diverted fluid flow may be caused tolubricate bearings 139 disposed in the rotary support 130 (e.g., thefluid may be permitted to penetrate and/or flow through the bearings139). In some such embodiments, the rotary support 130 at the non-motorend 121 may comprise one or more polymer or ceramic ball bearings 141adapted to be lubricated with water, a water-based fluid, and/or anothertype of fluid. The rotary shaft 131 and/or the bearing housings 143 mayfurther comprise a polymer/plastic to reduce the potential for particlegeneration and provide compatibility with the fluid used for lubrication(e.g., water although other fluids may be employed). The rotary support130 may also provide for venting of the flow of lubricating fluidoutward of the scrubber box 101 so as to purge any particles generatedby the bearings 139 and/or any undesirable chemicals associatedtherewith, and to prevent the same from entering the tank 103 (FIG. 1A).For example, a drain 144 may be formed within the rotary support 130that surrounds the rotary shaft 131 to allow any fluid that flows pastthe bearings 139 and along the rotary shaft 131 toward the tank 103(e.g., right to left in FIG. 6) to be collected and drained before thefluid enters the tank 103.

In another embodiment of the invention, a rotary union may be employedat an end 601 of the rotary shaft 131. For example, a Deublin model20211-600 rotary union with silicon carbide face mechanical seals orother suitable rotary union may be employed.

As shown in FIG. 6, the coupling element 119 may be employed to seal therotary support 130 from the tank 103. The coupling element 119 maycomprise a bellows or similar dynamic seal (e.g., a dynamic linearreciprocal seal). A static seal (not shown) may be employed at thejunction between the coupling element 119 and the tank 103 as indicatedat by reference number 603.

Increased Diameter Idler Roller

FIG. 7 is a side, schematic view of an inventive roller arrangement 145that may be employed within the scrubber box 101 of FIGS. 1A-2 tosupport and/or rotate the substrate W. With reference to FIG. 7, theroller arrangement 145 includes an idler roller 147 and two driverollers 149. The diameter of the idler roller 147 is slightly larger(e.g., 0.005-0.010 inches larger) than the diameters of the two driverollers 149 which, in some embodiments, are approximately 2.5 inches indiameter. In at least one embodiment of the invention, the angle betweenthe rollers 149, 147 may be about 50° as shown by angle θ₂, rather thana more conventional angle of about 40° as shown by angle θ₁. It will beunderstood that other angles also may be employed.

In operation, during rotation of the substrate W in a scrubber boxcomprising the above roller arrangement 145 of an idler roller 147 of arelatively large diameter and first and second drive rollers 149 of arelatively smaller diameter, each of the idler roller 147 and the firstand second drive rollers 149 may simultaneously achieve contact with,and reliably remain in contact with, the peripheral edge E of thesubstrate W as the substrate W rotates along with the idler 147 anddrive rollers 149. By contrast, in one or more known arrangements inwhich the respective diameters of the idler roller and the drive rollersat least are nominally the same, variation in the diameters of rollerdiameters within manufacturing tolerances around the nominal diametermay result in one of the drive rollers or the idler roller failing toachieve or maintain contact with the edge of the substrate duringsubstrate rotation.

In one or more embodiments, where the larger-diameter idler roller 147of the present invention contacts the edge E of the rotating substrateW, the idler roller may exhibit greater compressibility compared tocorresponding edge-contact regions on the drive rollers 149. Such anarrangement may, for example, ensure that contact between the substrateedge and the larger-diameter idler roller 147 does not result in thesubstrate edge being displaced away from either or both of the driverollers 149.

Also, in some such embodiments and/or in one or more other embodiments,the idler roller 147 may be equipped with an additional source ofrotational torque (e.g., besides the torque of the drive rollers 149 astransmitted by the rotating substrate W). For example, the idler roller147 may be equipped with a separate drive motor (e.g., motor 701 in FIG.1A) so that the idler roller 147 and drive roller 149 rotate atdifferent speeds (e.g., as to permit selective substrate edge cleaningvia sliding contact where the idler roller 147 contacts the substrateedge). In some such embodiments the idler roller 147 may be selectivelycoupled and/or decoupled from the additional source of rotationaltorque.

It will be understood that in other embodiments of the invention, theidler roller 147 and drive rollers 149 may be similarly sized.Furthermore, other arrangements of the drive and idler rollers may beemployed. For example, the idler roller 147 may be disposed between thedrive rollers 149.

Substrate Rotation Sensor

In one or more further embodiments of the invention, the idler roller147 (and/or one or more of the drive rollers 149) may be adapted toprovide a rotations per minute (RPM) reading. For example, FIG. 8 is aside, cross-sectional view of an embodiment of the idler roller 147. Asillustrated in FIG. 8, the idler roller 147 may comprise a housing 151,and one or more magnets 153 embedded in the housing 151 and adapted tointeract with a proximity sensor 157 (e.g. Hall effect-based sensors,inductive-based sensors, etc.). More specifically, as the idler roller147 rotates, the one or more magnets 153 may interact with the proximitysensor 157 as the one or more magnets 153 pass the proximity sensor 157so as to generate electrical pulses at a rate corresponding to a rate ofrotation of the idler roller 147. In some such embodiments, a controller155 may be adapted to receive the pulses and convert the pulses into anRPM reading of the substrate.

Water-Lubrication of Roller Bearings

As further shown in FIG. 8, in at least one embodiment of the invention,the idler roller 147 may employ a water-lubricated bearing 801. Forexample, an inlet 803 may be formed on a backside of a spindle housing805 about which the idler roller 147 rotates. The inlet 803 allows fluid(e.g., water) to travel toward and lubricate the bearing 801 asindicated by arrow 807. One or more of the drive rollers 149 may besimilarly configured.

In some embodiments, the idler roller 147 may comprise one or morepolymer or ceramic spherical bearings adapted to be lubricated withwater and/or a water-based fluid. The idler roller 147 and/or thebearing housing 151 may further comprise a polymer/plastic to reduce thepotential for particle generation and provide compatibility with thefluid used for lubrication (e.g., typically water although other fluidsmay be employed). The bearing housing 151 may also provide for ventingof the flow of lubricating fluid outward of the scrubber box 101 so asto purge any particles generated by the bearing 801 and/or anyundesirable chemicals associated therewith, and to prevent the same fromentering the tank 103 (FIG. 1A).

Slotted Rollers

FIG. 9 is a side perspective view of one of the drive rollers 149provided in accordance with another embodiment of the invention. Asshown in FIG. 9, the drive roller 149 includes a plurality of slots 901or other openings formed within each side of the drive roller 149. Inthe embodiment shown, 32 slots 901 are evenly spaced about thecircumference of the roller 149 and have a width of about 0.03 inchesand a depth of about 0.06 inches for an idler roller having a diameterof about 2.5 inches. Other numbers and/or spacing/dimensions of slotsmay be employed. The slots 901 preferably extend to (or below) thesurface of the roller 149 that contacts the substrate W. In this manner,the slots 901 allow liquid to escape from the surface of the roller 149that contacts the substrate W so as to increase the gripping forcebetween the substrate W and the roller 149. Holes or other surfacefeatures also may be employed, as described for example, in previouslyincorporated U.S. patent application Ser. No. 09/580,880, filed May 30,2000 (Attorney Docket No. 3874). The idler roller 147 may be similarlyconfigured with slots and/or other surface features.

Polymer Coated Motor Shaft

In yet another embodiment of the invention, the shaft of one or more ofthe brush motors 111 (FIG. 1A), drive roller motors (e.g., motors 1001and 1003 in FIG. 1A), or idler roller motor 701 (FIG. 1A) may include apolymer coating and/or polymer cap. Such a cap and/or coating mayprotect the motor shaft from any chemistry employed during substratescrubbing. For example, FIG. 10A is a partial cross-sectional view of afirst exemplary embodiment of a polymer capped motor shaft. Withreference to FIG. 10A, a motor 1005 is shown having a shaft 1007. Apolymer cap 1009, formed from polyphenylene sulfide (PPS) or anothersuitable material, is disposed around and coupled to a mounting bracket1011 of the motor 1005. Suitable seals (not shown) may be employed toseal the polymer cap 1009 relative to the motor 1005 and/or shaft 1007.Further, a gas purge channel 1013 may be formed within the polymer cap1009 to allow nitrogen or a similar purge gas to flow around the shaft1007 to further discourage fluid from traveling up the shaft 1007 towardthe motor 1005.

FIG. 10B illustrates an alternative polymer cap arrangement for themotor 1005 of FIG. 10A. In FIG. 10B, a first polymer cap or coating 1015is attached to and/or formed on a shaft elongation member 1017. Theshaft elongation member 1017, in turn, is coupled to the motor shaft1007 (e.g., via a set screw or other suitable mechanism not shown). Asecond polymer cap 1019 may be further coupled to the first polymer capor coating 1015 and to the bracket 1011, and employed to provide the gaspurge channel 1013 described above with reference to FIG. 10A. Suitableseals (not shown) may be employed to seal the second polymer cap 1019relative to the motor 1005 and/or first polymer cap or coating 1015.

The shaft elongation member 1017 may comprise the same material as themotor shaft 1007 (e.g., stainless steel), or another suitable material.By employing a separate shaft elongation member 1017, a more durablegluing or bonding process may be employed to secure the first polymercap or coating 1015 to the shaft elongation member 1017 than may beemployed on the motor 1005/motor shaft 1007. Likewise, unlike the motor1005, the shaft elongation member 1017 may be directly exposed to apolymer deposition process and then attached to the motor shaft 1007.

Brush Gap Calibration

As described above, the zero point for scrubbing brushes 106 a-b (FIG.1B) relative to the major surfaces of a substrate W, which correspondsto the largest value of r_(b) consistent with the brushes 106 a-b stillcontacting the major surface of the substrate W, may be found bymonitoring the torque T_(s) of the motor that drives the brushes 106 a-bas the brushes 106 a-b are moved to contact the substrate W. In analternative embodiment, instead of locating the zero point for scrubbingbrushes relative to a substrate by monitoring the torque of the motors111 that drive the brushes 106 a-b, a “zero-gap” position between thetwo scrubber brushes 106 a-b may be determined in order to calibrate theposition of the brushes 106 a-b.

Referring to FIG. 11, a brush gap calibration method 1100 may includethe following steps. According to the present invention, a gap betweenthe brushes 106 a-b may be incrementally closed while a first brush 106a is rotated and the second brush 106 b is stationary but free torotate. As indicated above, the brushes 106 a-b may normally be drivenby independent servo motors 111 that each include an encoder. In Step1102 the method begins. In Step 1104, the first brush 106 a may bedriven at a slow speed. In some embodiments, a slow speed is selected tominimize the chance that eventual impact between the brushes 106 a-bdamages either of the brushes 106 a-b. In Step 1106, the second brush106 b is not driven, the corresponding motor 111 coupled to the secondbrush 106 b is put in a “free wheeling” state, and the encoder of thecorresponding motor 111 is monitored. In Step 1108, the gap between thebrushes 106 a-b is closed an incremental amount. As the process 1100loops between Steps 1108 and 1110, the driven first brush 106 aeventually contacts the stationary second brush 106 b and causes it torotate from contact friction. At the point that encoder feedback of themotor 111 coupled to the stationary brush 106 b indicates that thestationary brush 106 b is being rotated, the position of the brushes 106a-b is identified as the zero-gap position and the process 1100 moves toStep 1112. In Step 1112, using the zero-gap position as a startingpoint, a defined amount of brush compression may achieved by furtherdriving the brushes 106 a-b together a predefined amount as describedabove. In Step 1114, the inventive calibration process completes.

In some embodiments, a controller (such as the controller 104 of FIG.1B) driven by software may be employed to automatically perform thiscalibration process after new brushes are installed, brush wearnecessitates recalibration of the zero-gap, and/or anytime there is nosubstrate between the brushes. There are several advantages to thiscalibration method. Additional sensors, calibration tools, andmeasurements are not required. Personnel are not required to contact theinside of the scrubber box. Variations in brush diameter and otherdevice tolerances are automatically compensated for by the presentinvention.

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For instance, the shape of thesupports 107, 109 in FIGS. 1A-3 is merely exemplary. In one embodiment,the supports 107, 109 may be more unshaped (e.g., so as to extendprimarily from one end of a brush down to the base 113, along the base113 and up to the other end of the brush). Accordingly, while thepresent invention has been disclosed in connection with exemplaryembodiments thereof, it should be understood that other embodiments mayfall within the spirit and scope of the invention, as defined by thefollowing claims.

1. An apparatus comprising: a linkage adapted to support scrubberbrushes, the linkage including: a base, a first brush support pivotallycoupled to the base, and a second brush support pivotally coupled to thebase; and an actuator adapted to pivot the first and second supports inconcert such that scrubber brushes supported by the first and secondbrush supports approximately simultaneously achieve contact with, orbreak contact with, respective major surfaces of a substrate.
 2. Theapparatus of claim 1 wherein the actuator is further adapted to exertsimilar degrees of compression against respective major surfaces of asubstrate when closed against the substrate.
 3. The apparatus of claim 1wherein the actuator includes a crank and rocker mechanism.
 4. A methodcomprising: inserting a substrate into a scrubber box; concurrentlypivoting opposing first and second brush supports together through asingle arc to engage a substrate with brushes supported by the first andsecond brush supports; and rotating the brushes to clean the substrate.5. The method of claim 4 wherein pivoting the first and second brushsupports includes rotating the first and second brush supports using asingle actuator so that an amount of motion of each brush support issubstantially equivalent and mechanically linked.
 6. The method of claim5 wherein rotating the first and second brush supports includes using acrank and rocker mechanism to achieve substantially equivalent motion ofboth brush supports.
 7. An apparatus comprising: a brush support adaptedto rotatably hold a scrubber brush; a motor adapted to rotate thescrubber brush held in the brush support; an actuator coupled to thebrush support and adapted to move the brush support to allow thescrubber brush to engage a substrate; and a controller coupled to themotor and actuator, and adapted to locate a zero point position of thescrubber brush based upon a change in torque exerted by the motor torotate the scrubber brush as the actuator moves the brush support.